bio 1.2.2 - Analyze how cells grow and reproduce in terms of interphase, mitosis and cytokinesis.
Each eukaryotic cell has a repeating set of events that make up the life of every cell, called the cell cycle. Although they vary in length depending upon the cell's function, the cell cycle for all cells can be described in three main steps. These three steps where the cell grows, matures, and carries out its life function are collectively called interphase, followed by mitosis, and cytokinesis.
The interphase is comprised of stages, G1, S, and G2, which begins the process in which:
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Stages of mitosis
![Picture](/uploads/2/8/1/7/28177325/7748614.gif?209)
Interphase:
- During interphase, the cell is engaged in metabolic activity and performing its prepare for mitosis
- Chromosomes are not clearly discerned in the nucleus, although a dark spot called the nucleolus may be visible
- The cell may contain a pair of centrioles (or microtubule organizing centers in plants) both of which are organizational sites for microtubules
![Picture](/uploads/2/8/1/7/28177325/8693897.gif?210)
Prophase:
- During prophase, chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes
- The nucleolus disappears
- Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres
- Some fibers cross the cell to form the mitotic spindle
![Picture](/uploads/2/8/1/7/28177325/8796447.gif?209)
Metaphase:
- Spindle fibers align the chromosomes along the middle of the cell nucleus
- This line is referred to as the metaphase plate
- This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome
![Picture](/uploads/2/8/1/7/28177325/4360369.gif?207)
Anaphase:
- The paired chromosomes separate and move to opposite sides of the cell
![Picture](/uploads/2/8/1/7/28177325/654535.gif?205)
Telophase:
- Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei
- The chromosomes disperse and are no longer visible under the light microscope
- The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage
![Picture](/uploads/2/8/1/7/28177325/2172882.gif?204)
Cytokinesis:
- This is the stage whenever the cytoplasm separates into two separate cells
- In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus
- In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.
Asexual Reproduction
Mitosis is a form of asexual reproduction. Asexual reproduction is the process of producing offspring without the use of gametes, or sex cells (sperm for a male, egg for a female). Asexual reproduction guarantees that the offspring will be both genetically and structurally identical to each other and their parent. It also allows one parent to rapidly produce offspring. For instance, the foxtail plant is considered a “weed” in certain parts of the Midwest. It is an annual plant that is able to produce enough seeds to cover an exposed area in one growing season. In one sense this is good, because it may prevent erosion; unfortunately, the area covered by the foxtail may be a farmer's field. It also increases the likelihood that the species will survive, simply because of massive numbers. The identical nature of the offspring is also a potential drawback because of a major change in the environment, or the blanket use of a biocide, or a hungry predator.
Control of the cell cycle lab
Here is a fun, interactive game that teaches you more about the cell cycle!
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